An example of conventional wind power generators is a rotor blade for a wind power generator disclosed in Korean Patent No. 0707132. Korean Patent No. 0707132 is intended to provide a rotor blade for a wind power generator, in which a plurality of air guide holes are formed through a disc and a plurality of air pockets are formed in areas having the air guide holes, thus protecting the rotor blade from strong and irregular wind blowing on the upper and lower surfaces of the disc in diagonal directions and guiding the wind blowing on the upper and lower surfaces of the disc, thereby efficiently accelerating both the rotation of the rotor blade and the rotation of the rotating shaft. Further, Korean Patent No. 0707132 is intended to provide a rotor blade for a wind power generator, in which a propeller shaft is provided at one end of a rotating shaft and is assembled with a universal coupling having flange couplings, so that the propeller shaft can be indirectly coupled to a gear box or to a power generator using another universal coupling, thus being easy to repair and being able to be selectively used with various power generators having different power generating capacities.
In order to accomplish the above-mentioned objects, Korean Patent No. 0707132 provides a rotor blade for a wind power generator, comprising: a rotating shaft having a first flange coupling in a first end thereof and rotatably supported by at least one bearing installed in a support frame; a disc mounted to the rotating shaft; a plurality of air guides formed through the disc and guiding wind blowing on upper and lower surfaces of the disc; a plurality of first wind collectors formed around upper and lower ends of the air guides, thus collecting wind blowing on the upper and lower surfaces of the disc and rotating the rotating shaft; a plurality of second wind collectors mounted both to the rotating shaft and to the disc, thus collecting wind blowing on the disc and rotating the rotating shaft; a first universal coupling having a second flange coupling in a first end thereof and coupled to the first flange coupling of the rotating shaft, with at least one vertical protrusion vertically formed on an inner surface of a mounting hole formed in a second end of the first universal coupling; and a propeller shaft having at least one vertical hole, which is formed in a first end of the propeller shaft and is inserted into the mounting hole such that the vertical hole can be fitted over the vertical protrusion and can be moved in a vertical direction, with both a third flange coupling and a second universal coupling provided in a second end of the propeller shaft.
In an embodiment disclosed in Korean Patent No. 0707132, the air guides are holes formed through the disc in an outer circumferential area of the disc, and these holes are spaced apart from each other at regular intervals. The first wind collectors are air pockets formed on predetermined areas on the upper and lower surfaces of the disc having the air guides such that the air pockets are opposed to each other and collect wind. Further, the second wind collectors are blades, which are formed on the upper and lower surfaces of the disc such that the blades extend in radial directions and are opposed to each other, and are securely mounted to the rotating shaft. The blades constituting the second wind collectors are curved and are concaved to a predetermined depth in locations close to one ends of the air pockets formed on the upper and lower surfaces of the disc.
The blades are mounted to inclined frames which extend from the rotating shaft and are attached to the upper and lower surfaces of the disc. One end of each air guide hole extends outwards such that the end of the air guide hole is exposed to the outside by a predetermined length compared to an open end of each air pocket. Further, the air pockets are configured such that the width and height of each air pocket is gradually reduced in a direction from the first to the second end of the air pocket and the air pocket has a tapering shape which has also both a semicircular appearance and a hollow structure.
According to tests of the rotor blade for the wind power generator of No. 0707132, the rotor blade can be protected from strong and irregular wind blowing on the upper and lower surfaces of the disc in diagonal directions and the wind blowing on the upper and lower surfaces of the disc can be efficiently guided, thereby easily accelerating both the rotation of the rotor blade and the rotation of the rotating shaft. However, the rotor blade for the wind power generator of No. 0707132 is problematic in that, when wind flows outwards while coming into contact with the inner surfaces of the blades constituting the second wind collectors, vortexes are formed in the wind at locations around the air pockets, thus disturbing a uniform rotation of the rotor blade.
Further, the wind power generator of No. 0707132 is advantageous in that it is easy to repair both the propeller shaft and the coupling structure between the propeller shaft and the gear box or the power generator indirectly coupled to the propeller shaft using the second universal coupling and the rotor blade can be selectively used with various power generators having different power generating capacities. However, the rotor blade is problematic in that the propeller shaft is vertically installed and cannot be smoothly rotated due to the weight thereof. Particularly, the rotor blade has no device for responding to changes in the length of the propeller shaft which occur in accordance with weather conditions, so that the rotating shaft cannot be smoothly rotated. Therefore, it is desired to provide a wind power generator, which can prevent the generation of vortexes in the wind on the rotor blade and can efficiently control the changes in the length of the rotating shaft due to either the weight of the rotating shaft or weather conditions.